This invention relates to the oxidation of olefins. In one of its aspects this invention relates to the use of a particular solvent in olefin oxidation.
Olefin oxides are extremely useful articles of commerce. They are used as starting materials for the preparation of humectants, lubricants, surfactants, polyethers useful in the preparation of polyurethanes, and the like. An especially useful olefin oxide is propylene oxide. Currently, propylene oxide is prepared from propylene by the classical two-step chlorohydrin route and by oxidation with tertiary-butyl hydroperoxide in the presence of catalysts such as molybdenum salts.
Both of these methods have inherent disadvantages. The chlorohydrin process requires two steps and, because it yields chlorinated by-products, removes expensive chlorine from the process. The tertiary-butyl hydroperoxide method requires the presence of an inorganic catalyst and yields tertiary-butyl alcohol in equimolar quantities to the olefin oxide produced. This tertiary-butyl alcohol must be sold or used.
Numerous reports have been made in the literature regarding methods for the liquid phase oxidation of olefins to olefin oxides with molecular oxygen. Many of these oxidation methods require the presence of catalysts or other additives or secondary treatment of the oxidation mixture with basic materials. Other oxidation methods require the use of certain solvents, such as esters of acetic acid or esters of benzoic acid. None of these liquid phase oxidation methods seems to have been successful enough to result in a commercially acceptable process.
It is therefore an object of this invention to provide a method for the liquid phase oxidation of olefins to olefin oxides with molecular oxygen.
Other aspects, objects, and the various advantages of this invention will become apparent upon reading this specification and the appended claims.